openstack-tox-py27 : pre-install python packages

As noted inline, we dropped the install from the base images.  This
should pre-install python2/-dev to return us to about the same state,
but just for the legacy jobs.

Change-Id: Ia8cf6911cb48dfbef59fcf890d4b29d162dc11ad

playbooks/tox/py27.yaml

@@ -0,0 +1,17 @@
+# NOTE(ianw) 2023-02-08:
+#
+# In change [1] we dropped python-dev packages and thus stopped
+# installing python2 packages.  Jobs should be relying on bindep for
+# this, but many on stable branches aren't.  Since the python2/3
+# transition as a weird time, we'll just install python2 packages
+# here.
+#
+# [1] https://review.opendev.org/c/openstack/project-config/+/872476
+
+- hosts: all
+  tasks:
+    - name: Install Python 2.7
+      package:
+        - python
+        - python-dev
+      state: present

zuul.d/jobs.yaml

@@ -157,6 +157,7 @@
 
       Uses tox with the ``py27`` environment.
     branches: ^(?!stable/rocky).*$
+    pre-run: playbooks/tox/py27.yaml
     irrelevant-files: &common-irrelevant-files
       - ^.*\.rst$
       - ^api-ref/.*$